Auto-Control Hyperthermia Applications of Lafesih Nanoparticles With First-Order Phase Transition
Özet
Magnetic hyperthermia applications demand precise temperature control within the
targeted region to safeguard the well-being of surrounding healthy tissues during cancer
treatments.To achieve this objective, a temperature control mechanism can be
implemented based on the heating properties of magnetic nanoparticles, which is called
auto-control magnetic hyperthermia. This can be accomplished by utilizing magnetic
materials that undergo a first-order phase transition around the Curie temperature. LaFeSi
compounds, well-known for their magnetocaloric applications, have the potential to be
employed as a material for auto-control magnetic hyperthermia therapy applications.
However, Curie point of LaFeSi compound is significantly lower than the necessary
temperature required to eradicate cancerous cells. In this thesis, we studied on a method
to elevate the Curie temperature of LaFeSi compounds to points adequate for inducing
protein denaturation in cancer cells through heating, achieved by hydrogenation of the
compound. For this purpose, LaFe11.57Si1.43 ingots are initially fabricated using the arc-melting technique. Subsequently, the compounds exposed to high-temperature heating
for several days to ensure homogenization. Samples are then hydrogenated under 5 bar
H2 atmosphere using a Sievert-type apparatus. Following this, the samples are annealed
under vacuum conditions for varying durations to fine-tune the Curie temperature of the
compounds. Samples are also mechanically milled to obtain nanoparticles.
The Curie temperature is succesfully tuned from 200 K to 341 K by changing the H
amount in LaFe11.57Si1.43Hy compounds. The LaFe11.57Si1.43H1.41 samples with cubic
NaZn13-type structure, demonstrated efficient heating capabilities. Remarkably, the
samples retain 1st-order magnetic phase transition characteristics and cease heating
around 50 °C when subjected to an alternating magnetic field. The specific absorbtion
rate is therapeutically significant, 10.9 W/g at an applied field of 26 kA/m and a frequency
of 300 kHz. Given these exceptional properties, LaFeSiH compounds emerge as
promising candidates for deployment as therapeutic materials in cancer treatment.
